Optical Design And Application For LED Low-location Lighting

Characterized by low-location lighting, little light pollution, convenient installation and simple maintenance, low-location lighting has been applied more frequently in the field of lighting with the progress of society and the development of science. Traditional low-location lighting has some disadvantages, such as imprecise light distribution, poor functional lighting and inclination to landscape lighting. Compared with traditional light sources, LED(Light Emitting Diode)shows more advantages. Appropriate optical design of LED may improve light energy distribution so that LED may meet the requirements for lighting. Therefore,LED is an alternative for traditional sources that has greatly improved low-location lighting. As for the lens, silver plated reflector has many advantages including low light pollution, satisfactory lighting effect, excellent heat dissipation, easier control in the shape and low cost. This paper will present three types of low-location lamps,dual-light LED advertising light boxes, LED guardrail lamps and large outdoor column billboard LED projector lamps. Meanwhile,three different reflective covers that meet the requirements for lighting were designed.In view of large-area asymmetric lighting of LED advertising light boxes within a short distance, a vector design method based on light distribution curves is proposed to design reflective covers of LED advertising light boxes. According to lighting distribution requirements for target surface and the changes of illumination after adding a reflector cover, light distribution curves for advertising light boxes that satisfy the requirements for uniform lighting were established, constructing an effective overlay and compensation of direct and reflective light while calculating angles to project all light sources. A new scheme was thus put forward to design dual-light advertising light boxes. The simulation results suggested that the uniformity of target illumination was up to 85% and energy utilization rate exceeded80%.In light of the shortcomings and defects of traditional guardrail lamps, a styleof LED guardrail lamp was designed to accommodate urban road lighting so that LED guardrail lamps could illuminate both sides of the road and provide uniform illumination after optical superposition. By comparing requirements for road illumination to illumination distribution without reflector cover, energies of LED light sources were distributed to establish a corresponding relationship between angles of emergent light and the coordinate of lighting points on illumination plane.Reflective light of light sources was divided to correspond to light energies that were necessary for the compensation of road areas. Reflective covers were constructed to realize asymmetrical and large-angle light emission. Furthermore, light sources were expanded into line light sources. A design model that was convenient and efficient for calculation was proposed for fog light covers. The cover design optimized the light distribution curves and the requirements for flicker control in installing lamps were taken into consideration during the installation. The results showed that luminous efficacy was above 81% and road lighting met Standards for Designing Urban Road Lighting.Different from the existing LED projector lamps, a new model of projector lamps was used so that the light-emitting surface of LED light sources would face towards a reflective cover instead of illuminated surface. In this way, it greatly overcomes the defect that traditional reflective covers emitting light at large angles could not control the light near the center of LED light sources. A category of reflective cover that was appropriate for outdoor column billboards was designed by grid partition. Based on theories of edge light and laws of energy conservation,grids were divided for light sources and target surface by analyzing relationships between angular distribution of LED light sources and the illumination of target surface, determining the corresponding relationships of energies and thus designing reflective covers for free-form reflective surfaces. According to simulation results,uniformity of target illumination was 71.0% and energy utilization rate was 88.4%.